Work was done on this invention primarily to provide a container for marketing cheese slices. The product could be sold to the public, then the customer could open the package, extract some of the cheese slices, and then reclose the package to reduce the oxidation and drying of the cheese. It is desirable to increase the shelf life of all food products which could be contained within the package, and restricting the flow of oxygen to and moisture from the food product tends to prolong its shelf life. The reclosability of the package itself also helps to insure that dust and other debris floating in the air will not have access to the products after it is opened.
The tray and cover combination of this invention is useful for other products than cheese and, indeed, the package could be reused to hold other products after the goods initially contained have been used and the package washed for reuse.
Containers which are stackable and having corner shelves to hold them in separated position are disclosed in the patent to Fornas, U.S. Pat. No. 2,960,134.
Containers which are resealable or partially resealable after the contents of the package are partially used are not new. A patent to Stevens et al, U.S. Pat. No. 3,082,903, discloses a container with an integral lid, the two parts being hinged together. A patent to Schechter, U.S. Pat. No. 3,214,074, teaches a container which is hermetically sealed at the top, while below the hermetic seal is a reusable inner lid. The lid fits in a groove around the inside surface of the tray but the tabs allowing removal of the lid also allow air to reach the package contents. The structure of the lid inherently allows the incursion of oxygen and airborne debris.
A patent to Sosin, U.S. Pat. No. 3,410,698, discloses a package for luncheon meats where the two halves of the package are hinged along one edge and are virtually mirror images of each other. The disclosure indicates that it is "resealable", but there is nothing in the disclosure which tells one how the resealing would take place. Apparently the only force to reseal the package is gravity.
A patent to Muehling et al., U.S. Pat. No. 3,483,964, discloses a conventional blister pack which is hermetically sealed at the outset, but has no substantial disclosure of how one would reseal the package to prevent the incursion of undesirable oxygen and debris after it is opened.
The patent to Lundquist, U.S. Pat. No. 3,502,486, discloses a reusable, four sided, blister pack for food where the tray portion of the container is hinged to the lid portion along one side, and a resealable edge is provided on the diagonally opposite side. There is no means for resealing along the other two of the four sides.
The patent to Constantine, U.S. Pat. No. 3,759,416, discloses vertically extending ribs in a container sidewall to provide mechanical stability.
The patent to Wyslotsky et al., U.S. Pat. No. 4,427,705, discloses a reusable package for commestibles involving two parts pressed together to hold goods therebetween and having a detent-type latch means along one side.
The patent to Wise, U.S. Pat. No. 4,848,580, discloses a tray and cover formed of thermoplastic resin having vertically extending flutes in the sidewall to increase mechanical stability.
There is a need in the industry for a food package which is resealable or reclosable by positive mechanical means after the package has been opened and a portion of the contents removed.